Listen the first time so the teacher doesn't have to keep repeating themselves and holding up the class, and If you didn’t hear the first time then ask someone close to you who did hear.
Purposefully doing things to annoy other people is only funny to you, not to the entire class.
Don't sit there all class and do nothing, at least try to get some work done.
Some classes are easy enough that you can pass them by just simply doing your work, SO DO YOUR WORK.
When the teacher says “Discuss it at your table”, Actually discuss it instead of looking around at eachother waiting for one person to be the first to say something.
Don't be afraid to answer a question if you know the answer.
Don't be afraid to disagree.
Getting work done before the bell ends may not be important to you  but it is to other people.
Don't hesitate or doubt yourself.
Reflection: After writing these things it made me realize that I also have to work on some of these things, and by working on them it can make me a better classmate and student.